Complexation of DNA Block Copolymers with Ionic Liquids

Block copolymers containing DNA and synthetic polymer segments are a special class of anionic-neutral copolymer materials that can potentially interact with cationic molecules to form polyelectrolyte complexes. Ionic liquids (ILs) are green solvents consisting of tunable cationic and anionic constituents, and their interaction with biomolecules, including DNA, has been reported. In this study, we synthesize DNA-b-poly(ethylene glycol) (DNA-b-PEG) block copolymers and investigate their complexation with a number of biocompatible ILs. DNA-b-PEG is prepared by coupling chemistry between amine-functionalized DNA and N-hydroxysuccinimide ester activated PEG. Thermal annealing is then employed to induce complex micelle formation. The binding strength of DNA-b-PEG and IL is determined by the hybridization state of the DNA, with double-stranded DNA (dsDNA) showing stronger binding to ILs than single-stranded DNA (ssDNA). The morphology and stability of the complex micelles are also examined, and they are influenced by the concentration of the IL and the alkyl chain length of the IL cation.